The present invention relates to a correction system for synchronizing an analog (i.e. hands) display section and in particular to a correction system for enabling the timepiece user to easily and rapidly confirm and if necessary adjust the state of synchronization between the content of a hand position memory circuit and the hands display section, without regard to the count state of the timepiece timekeeping circuit when such confirmation and adjustment are carried out.
A loss of synchronization between the content of the hand position memory circuit and the hands display section of such an electronic timepiece can occur for a variety of reasons. It will of course be necessary to initially establish such a state of synchronization when a battery is first inserted into the timepiece, and in general it will be necessary to adjust the operation of hands display section to provide exact synchronization each time the battery is changed thereafter. In addition, there are certain conditions, such as operation at extremely low temperatures, or operation in the vicinity of strong alternating electro-magnetic fields, in which the stepping motor of the timepiece may occasionally fail to rotate correctly in response to drive pulses applied thereto, while the timekeeping circuit continues to operate correctly, so that the time indicated by the hands display section becomes erroneous to some extent.
In the prior art, the hands display of an electronic timepiece has generally been arranged such that the user adjusts it (i.e. sets it into a state of synchronization such as to display a precisely identical time). Such an arrangement is troublesome for the user especially in a case where the electronic timepiece is provided with both analog and digital display capabilities, since if for example the time displayed by the digital display section is known to be accurate or has just been adjusted to an accurate value by the user, then if it is attempted to set the time indicated by the timepiece hands to correspond precisely to that indicated by the digital display section, difficulty will be encountered due to the fact that the time indicated by the digital display section will be constantly changing, in accordance with changes in the count contents of the timepiece timekeeping circuit. It especially desirable to ensure that the time indicated by the hands of such a timepiece corresponds precisely to that indicated by the digital display section, if the timepiece is provided with additional display functions, such as a preset alarm time display function, a stopwatch display function, etc, and if the hands are to be used to indicate time information for one or all of such additional functions. This will be apparent in the case of a timepiece equipped with a stopwatch function, in which both the hands and the digital display section should always start off precisely from an indication representing zero, i.e. the 12:00 position of the hands. Various methods have been proposed for synchronizing the hands display and digital display of an electronic timepiece. One method which has been proposed has been to provide electrical contacts on a part of the wheel train which drives the hands, in order to sense the hands positions electrically. However, the construction of such a timepiece is complex and the configuration is not suitable for providing a very thin and compact wristwatch. In addition, the manufacturing cost is high, and problems arise with regard to reliability of the contacts, and in addition energy is consumed by rubbing against these contacts. For such reasons, such timepieces have not been actually manufactured.
It is an objective of the present invention to provide correction means to enable the information indicated by the timepiece hands display to be easily and accurately set to correspond to the time value of a hand position memory circuit irrespective of the current count state of the timepiece timekeeping circuit. This is accomplished by purely electronic circuit means, which enable the user to instantly check on the state of synchronization between the content of the hand position memory circuit and hands display at any time, and to precisely adjust that state of synchronization in an extremely simple and rapid manner. Such a correction system can be implemented by the addition of a comparatively small number of circuit elements to the timepiece IC chip, so that no significant increase in manufacturing cost will be incurred by incorporation of a system according to the present invention into an electronic timepiece.